Method of treatment of nonferrous alloys



Patented July 28, 1931 4 UNITED STATES PATENT oFnc EDMUND MERRIMAN WISE, OF CINCINNATI, OHIO, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO THE INTERNATIONAL NICKEL COMPANY, INC., OF NEW YORK, N. Y., A

CORPORATION OF DELAWARE METHOD OF TREATMENT OF NONFERROUS ALLOYS No Drawing.

oping a high degree of strength and hard ness.

The primary object is to provide an improved method of imparting strength and hardness to alloys of the character mentioned. This method is applicable to the "reatment of known alloys and also to alloys in which copper, nickel and tin are employed in proportions hitherto not known to. be available.

The alloys referred to are useful for castng purposes and for cold rolling. The cast material, as well as the rolled material, can be heat treated at any suitable stage of fabrication to develop strength and hardness;

The alloys referred to contain essentially topper, nickel andetin, but may contain, also, small percentages of other metals, or other materials, such as lead, zinc, iron, aluminum, titanium, silicon, phosphorous, carbon, magnesium, etc. 7

The alloys amenable to the treatment to be described herein comprise copper and nickel which combinedly constitute the main percentage of the alloy, and tin which may con- 3 stitute not less than 3 to not more than 30% of the combined copper, nickel and tin present in the-alloy.

Preferably the percentage of the tin, based upon the copper, nickel and tin in the Application filed September 3, 1927. Serial No. 217,541.

able to use the manganese in a percentage exceeding 5% of the nickel.

Small amounts of iron, lead, aluminum, or s1l1con may be present Without harm, although for material that is to be rolled, these constituents should ordinarily not' exceed about 1%, combinedly. Zinc may-bepresent and cheap'ens the alloy. .In small quantities, 1t may be advantageously used, but in alloys containing a high nickel content, it is not desirable to employ more than a small percentage of zinc. Ordinarily, the zinc should not in any case exceed 10% and if the nickel content is above 25% of the alloy, it is best to exclude zinc. 1

The alloy may be formed by melting the materials and casting the metal in ingots. If preferred, the metal may be heated considerably above the melting point and the molten metal may be poured, at-this high temperature, into the ingot molds. No particular difficulties are experienced in casting the maalloy, considered as 100%, is not less than terial, but it is desirable that the carboncon- 5%, or greater than 15%. Reasonably good. results may be obtained within the range ofabout 4% to 15% tin. The percentages of nickel and copper in the alloy, considering -tin, nickel and copper as 100%, may-vary tent of the alloy shall be kept as low as possible.

The alloy may be formed by diffusing tin into the surface of an article formed from a suitable alloy of copper and nickel. The article might be made of an alloy-of 40% nickel and 60% copper. Upon heating for some hours at about 850 0., in a suitable container in contact with an alloy containing 25% ton and copper, the surface of the article would be converted into analloy of copper, nickel and tin, which" could 'be heat treated as hereinafter described.

In accordance with the present invention, the alloy can be softened at any desired stage by annealing the alloy, preferably for at least two hours, at a temperature ranging from 600 C. foran alloy containing about 5% of .riod of fifteen minutes to several hours. ,has been found that a temperature in the nickel, to about 900 C.950 C. for an alloy contai'ni about 50% of nickel; and then rapidly, cooling the alloy, preferably by quenching it in water or oil. The annealing or homogenizing temperature chosen should be that best suited to the particular alloy and should always be below the melting point of the alloy. The alloy can then be hardened nd strengthened by reheating to atemperature ranging from about 200 C. to about 550 C. and aging at such a temperature for a pe- It neighborhood of 300 C.450 Caordinarily is best suited to the purpose of hardening and strengthening the alloy. Itis to be remarked, however, that a lower degree of temperature, in the hardening and strengthening process,

' calls for a longer period of heat treatment.

' several hours, the temperature employed de-.

stated The appropriate temperature should be selected, of course, consonant with the proportions ofthe metals in the alloy. As noted above, the degree of temperature best suited to the annealing operation increases with' the nickel and tin content of the alloy; and als'o the temperature best suited to the hardening and strengthening treatment increases with the nicket content.

As an example of the treatment of a copper-nickel-tin alloy in accordance with the present process, the following is given:

The alloy is produced by melting the metals and casting an ingot; the cast alloy is then annealed for a prolonged period of time, preferably, at least two hours, at a temperature of preferably 600 to'950 C.,depending upon the nickel and tin content; the highly heated alloy is then rapidly cooled, as by quenching in water or oil, thus producing a soft metal; the alloy is then rolled or otherwise fabricated, as desired; and, finally, the alloy is hardened and strengthened by reheating to a temperature ranging from 200 C. to 550 C. and aging-for a period of time, preferably An alloy composed of copper, 7 43% nickel, and 7.57% tin was quenched from an annealing temperature of 800 G. This material showed an ultimate tensile strength of 61,000 pounds per square inch, and gave an elongation of 50% in the testing operation.

The same material quenched from an annealing temperature of 800 C. was aged dur-' ing a period of two hours at 300 C. This material showed a tensile strength of 105,500 pounds per square'inch and an elongation of 5% under test.

The relative hardness of the materials after the annealing process and after the.

hardening process were, for the former about 50 Band for the latter about 99 B on'the Rockwell scale of hardness.

As another illustration on this'point, an alloy consisting of 45%. copper,40% nickel and 15%tingave a Rockwell G hardness of- 8 after the material had been quenched from an annealing temperature of 950 C. The same material after aging at a hardening temperature of 450 C. for one hour, followed by an aging at 400 C. for fourteen hours, gave a 49 Rockwell C hardness and tioned, namely 200 C.550 (1, and aging at such temperature, results in the precipitation in the body of a compound of nickel and tin, or of copper and tin, which is distributed throughout the body and has the effect of greatly hardening the body and increasingitstensile strength greatly. While the phenomenon of the formation of a precipitate in the body .of the compound is indicative of completion of the hardening'and strengthening operation, it is, of course, true that the desired result is not due to an instantaneous change, and accordingly the invention is not to be unduly limited. A condition of incipient precipitation, or a sufficiently close approach to the point of precipitation to give the desired effect, is to be regarded within the spirit of the invention.

After annealing at a temperature of from 600 .to 950 (1., the alloy maybe allowed to cool very slowly -or may be held for several hours at a temperature between 500 C. and 600 0. Either treatment will result in the formation of relatively large sized particles of a nickel-tin or copper-tin com-- pound in the alloy. The alloy is then worked, by rolling, pressing, turning, hammering, or the like, as desired. Subsequently, the alloy is heated to a temperature suflicient to dissolve the precipitated particles (annealing temperature) is then quenched and thus rendered soft; and finally the material is reheated to the age-hardening temperature, namely 200 C to 550 C., and is hardened at this temperature for a suitable period of time, depending on the results desired. During this hardening treatment, precipitation of anickel-tin compound or I phase occurs, and it is assumed that this phenomenon increases the hardnessand' tensile strength of the material. 1

It is preferred, for many; purposes, to'employ from 60 to 90% copper in the alloy, 'n which case the percentage of nickel preferably ranges from about 33% down to 3.5% and the minimum percentage of tin preferably ranges from about 10% to 3.5%. On the other hand I have discovered that a good alloy can be produced by employing between 35% and 50%-of nickel, together with at least 7.5% to 12% of tin and the remainder of the 100% being copper, the tin content increasing with the nickel content of the illoy but not necessarily in the exact ratio.

I have discoveredthat the copper-nickeltin alloys which'yield the best results under the treatment herein described have the various metals of the alloy present in about the proportions indicated by the following table: hrz, 6.0% 5.5% 5% 5% 5.5% 6% .7% 13% 9% 11%13% Nicke1- O 1pper- For an alloy which is to be rolled, the tin content should not exceed 10%. Where a cast product is desired for use, the tin content may be as highas 15% or 20%.

The proportions may varyfrom those expressed in the table, but ordinarily'it will not be found desirable to decrease or increase the tin morethan about one-sixth of that stated in the table for any of the given tin- '1ickel-copper compositions. I

From the description given, it will be understood that/the improved process involves a hardening and strengthening step by means-of heat treatment at a range of emperature which permits the precipitation of a tin-nickel compound in a fine state of subdivision within the body of the alloy and this hardening and strengthening step preferably follows a previous annealing step at much igher range'of temperature which may be referred to as the homogenizing range, the alloy, being preferably quickly cooled from the 'high temperature, as by quenching inliquidf'before subjecting the xll'oy to the hardening. and strengthening heat treatment.

It is possible to harden castings of these copper nickel tin alloys,'particularly chill -castings by heating to the age hardening temserature 200 C. to 500 C. without'having previously heated said castings to the high homogenizing temperatures. A small chill casting containing 80% Cu, 10% Sn and 10% Ni, which had a Rockwell hardness of 70 B 65 is .cast,.hardened to 90 B on reheating to- I strength.-

350 C. for twenty minutes. For castings that are to be used for bearings and the like, this treatment may be desirable. It will be understood thatthe castings referred to in this paragraph may be such as are cast and cooled in any usual way.u However, in those .cases where the alloy is subjected to homogenizing treatmentand thenquickly cooled, it should be understood that such quick cool-- mg may be eflected in any desired manner. For illustration, quick cooling should be understood as to include ordinary air cooling,-

as distinguished from the very slow-cooling noted above, where some means for retarding the rate of cooling is employed, such as allowing cooling to occurxat a very slow rate in a furnace.

- The composition set forth in the foregoing table conforms approximately (within the limits of 5% to 50% nickel) to the following formula with respect to tin andv nickel, the remainder-of the 100% being represented by the copper:

tin=4.9 .00578 nickel 13) 2 Such a formula may be employed for calculating the percentages of theiseveral metals,

tin, nickel and copper, which yield the best results when treated by the improved process.

A more flexible and reasonably satisfactory formula-may be stated as follows:

tin=7.5+.00578 nickel -13) :':3, the percent of nickel being not substantially less than 4% and not substantially more than 50%,- the remainder, of 100% being princi pally copper.

Alloys of.

They are resistant to atmospheric corrosion and to quite an extent to the action of acids and alkalies and, ashas been indicated, when treated by the improved process, the alloys are very hard and possess a high tensile The presence in the alloy of other elements or materials which do not adversely affect the amenability to the treatment described, is not to be understood as a departure from the invention. The foregoing detailed description has been given for clearness of understanding only, and no unnecesary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

' What I regard as new, and'desire to secure 3 to 50% Ni; the remainder Cubased onan aggregate of 100% of the three metals men- 'tionedwhich comprises subjecting said alhe character described may be a advantageously vused in many situations.

loy to homogenizing treatment at a temperav ture below the melting point of the alloy and not substantially below 600 0., quickly cooling said alloy.

and then 2. The step in the treatment of an alloy of the composition stated in claim 1 which oomprises hardening and strengthening said alloy by heat treatment within the range of 200 C.

4. In the treatment of an alloy having the composition stated in claim 1, the steps which comprise: subjecting the alloy to a working or fabricating operation; and afterwards further hardening and strengthening the product by heat treatment within a range of 200 C. to 550 C.

5. In the treatment of an alloy having the composition stated in claim 1, the steps which comprise: subjecting the alloy to a working or fabricating operation; afterwards subjecting the product to homogenizing treatment within a range of 600 C. to 950 (3.; then quenching the product; and subsequently hardening and strengthening the product by heat treatment within a range of 200 C. to 550 C. p q

6. The process of treating a Cu-Ni-Sn a1- loy having the tin and nickel substantially in the proportions indicated by the following formula:

% tin7.5+.00578 'nickel13) :*:3,

the per cent of nickel being not substantially less than 4% and not substantially more than and the percent of tin being substantially in the range of 4 to 18 the remainder of an aggregate of 100% of the three metals being principally copper, which comprises subjecting the alloy to homogenizing treatment within a range of 600 C. to 950 C., and

i position stated in claim 6 by heat treatment within a range of 200 C. to 550 C.

600 (1, and then quickly cooling said alloy.

11. The process which comprises: subjecta ing an alloy ofthe composition expressed in claim 9 to a homogenizing treatment at a.

temperature below the melting point of the Cu-Ni-Sn allo andg not substantially below 600 C.; quic 1y cooling said alloy; and hardening and strengthening the alloy by heat treatment within the'range of 200 C. to 500 C.

12., subjecting an alloy having the composition stated in claim 9 to mechanical work ing, and subsequently hardening and strengthening said alloy by heat treatment within the range of 200 C. to 550 C.

13. The method of treating a'Cu-Ni-Sn cast alloy comprising (expressed in per cent) :'Sn 5% to 15%; nickel 3%% to 25% remainder Cubased upon an aggregate of 100% of the three metalssaid method comprising hardening and strengthening. said alloy by heat treatment within the range of 200 C. to 550 (3.,

14. Thelprocess which comprises subject-- ing to homogenizing treatment within a 90 range of 600 C. toc950 C. a Cu-VNi-Sn alloy, having the composition expressed in claim 13, quickly cooling thealloy' and subsequent- 1y hardening, and strengthening the alloy by heat geatment within a range of 200 C. to 550 15. The process which comprises: subjecting an alloy of the composition expressed in claim 9 to a homogenizing treatment at a temperature below the melting point of the Cu- 9 'Ni-Sn alloy, and not substantially below 600 0.; quickly cooling said alloy; subjecting said alloy to mechanical workings; subjecting the worked alloy to a homogenizing treatment at a temperature below said melting point and not substantially below 600 C.; again quickly cooling the alloy; and hardening and strengthening said alloy by heat treatment within the range of 200 C. to 550 C. v

EDMUND MERRIMAN WISE.

8. The process which comprises hardening and strengthening an alloy having the composition stated in claim 6, after said alloy has been treated in the manner specified in claim 7 by heat treatment within a range of 200 C. to 550 C. 4 i

9. The process of treating a. Ou-Ni-Sn alloy comprising (expressed in per cent) Sn=e;/ +.1(% Nl 5), and not less than 2.65% and not more than 20% Ni 3 to 50% remainder Cubased on an aggregate of the three metalssaid process comprising hardening and strengthening said alloy by heat treatment within the range of 200 C. to 550 C.

10. Subjecting an alloy of the composition expressed in claim. 9 to homogenizing treat- 'ment at a temperature below the melting point of the alloy and not substantially below 

